Signal lamp



FIG. 1 is a rear perspective view of my new design for a signal lamp;

FIG. 2 is front perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is rear elevational view thereof;

FIG. 5 is a right side elevational view thereof with the left side elevational view being a mirror image of the right side elevational view;

FIG. 6 is a front elevational view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for a signal lamp, as shown and described. 